In vitro callus induction and micropropagation of Thymus persicus (Lamiaceae), an endangered medicinal plant

Abstract This is the first attempt towards an efficient regeneration protocol for an endangered and valuable medicinal plant, Thymus persicus using in vitro callus induction and indirect organogenesis. Callus induction was performed on MS medium supplemented with different concentrations of NAA and 2,4-D, alone or in combination with BAP and KN. Maximum callus induction (100%) was achieved from internode explants cultured on MS medium fortified with 2.0 mg L-1 NAA and 0.5 mg L-1 KN. The highest frequency of shoot multiplication (96%) was observed with 2.0 mg L-1 BAP+1.0 mg L-1 NAA. The maximum number of rootlets (16.6 ± 1.4) was induced on half-strength MS medium with 0.5 and 1.0 mg L-1 IBA. Rooted plantlets were then successfully grown and acclimatized in the greenhouse with a 70-85% survival rate. The benefits of the protocol described here include all-year-round application, germplasm conservation, suitability for commercial production and also for the biotechnological production of pentacyclic triterpenoids.